#include <stdio.h>
typedef struct clock
{
    int hour;
    int minute;
    int second;
}CLOCK;
void Update(CLOCK *p)
{
    p->second++;
    if(0==p->second%60)
    {
        p->second=0;
        p->minute++;
    }
    if(0==p->minute%60&&p->minute!=0)
    {
        p->minute=0;
        p->hour++;
    }
    if(0==p->hour%24)
        p->hour=0;
}
void Display(CLOCK *p)
{
    printf("%02d:%02d:%02d\n",p->hour,p->minute,p->second);
}
void Delay()
{
    int t;
    for(t=0;t<750000000;t++);
}
void main()
{
    CLOCK clo1;
    CLOCK *p=&clo1;
    int i;
    clo1.second=0;
    clo1.minute=0;
    clo1.hour=0;
    for(i=0;;i++)
    {
        Update(p);
        Display(p);
        Delay();
    }
}
